Humans survived off rodents in the mountains during the last ice age, study says

CNN  — 

In Ethiopia during the last ice age, our human ancestors lived high in the Bale Mountains, using obsidian tools and hunting giant rodents, according to a new study. It’s the earliest evidence of high-altitude prehistoric living in a rock-type shelter.

Previously, it was believed that high-altitude living didn’t occur until later in human history. Recent studies are shedding light on the different living habits of our predecessors.

The study was published Thursday in the journal Science.

An international team of researchers including archaeologists, soil scientists, biologists and paleoecologists found evidence at the Fincha Habera settlement that they inhabited the mountains 45,000 years ago during the Paleolithic period.

The Bale Mountains sit 13,123 feet above sea level in southern Ethiopia. Living on the mountain means dealing with fluctuating temperatures, low oxygen, and a lot of rainfall.

But plateaus free of ice in the mountains provided a better home than the dry valleys.

Some groups of people living in Ethiopia today are able to handle lower levels of oxygen, and the researchers believe this might be why.

“Because of these adverse living conditions, it was previously assumed that humans settled in the Afro-Alpine region only very lately and for short periods of time,” said Bruno Glaser, study author and expert in soil biogeochemistry at Martin Luther University.

The researchers found evidence of clay fragments, stone artifacts and even a glass bead.

“We also extracted information from the soil as part of our subproject,” Glaser said.

Only the top layer of the soil has changed over time, making the soil a perfect way to test their palaeothermometer to track temperature, humidity and precipitation in the area over time.

They learned that at the time people were living there, the area was out of the way of glaciers. As they melted in phases, plenty of water was available for the inhabitants of the settlement.

Water not only nourished the people there, but their food source as well: giant mole-rats. Their scorched bones were uncovered at the site, proving that roasting was the preferred method of consuming them.

There was also a rock outcrop nearby full of volcanic obsidian, which they used to make tools to hunt the rodents.

“The settlement was therefore not only comparatively habitable, but also practical,” Glaser said.

It was also inhabited a second time and used as a hearth 10,000 years ago. The researchers aren’t sure if this was a permanent habitat either time as the people would have been foragers.

“For the first time, the soil layer dating from this period also contains the excrement of grazing animals,” Glaser said. Evidence of bovines and hyenas was also uncovered.

Living in high altitudes often requires a higher-calorie diet and reduced physical strain, which the plentiful water and easily hunted food source provided.